October 2018 – September 2023
Apple replant disease (ARD) causes significant economic losses across all major apple-growing regions worldwide. The disease etiology is not well defined and expresses as the poor growth of newly planted trees. This problem is exacerbated in Europe by the removal of several effective chemical soil fumigants. Recent results at NIAB EMR suggested that ARD is likely to be caused by several organisms: lack of specific beneficial microbes (particularly bacteria), fungal and oomycetes pathogens, and exacerbated by nematodes. Thus, in the absence of broad-spectrum fumigants, reducing ARD requires careful soil management to improve soil structure (particularly microbiota), especially in nurseries where young trees are grown in a high density.
In this project, Chris is trying to understand how various soil management practices (including amending soils with specific microbes) will impact soil quality in terms of ARD and canker development. In addition, he is also studying soil microbial dynamics under climate change scenarios: combinations of elevated CO2 x temperature x water potential stress.